Blair warns on threat to UK

While making no comment on specific intelligence or reports, such as a threat to release poison gas on the London Underground, he said that the group would do all it could to launch fresh attacks.

He told the Daily Mirror that the "centre of their [al-Qaida's] activities" in Afghanistan had been destroyed, but there were "tentacles" left all over the world.

"It is certainly trying to plan attacks on virtually any country, frankly, as we saw with Bali, and yes there is a real and serious threat, there is no doubt about that at all," said Mr Blair.

"We have to try and do everything we can to avoid it, whilst letting people live their normal lives."

The interview echoed comments the prime minister made to the lord mayor of London's banquet last week when he revealed that British intelligence gives him fresh warnings every day of a terrorist attack.

The shadow home secretary, Oliver Letwin, today urged David Blunkett to appear before MPs over an alleged plot to release poison gas on the tube and the arrest of three men in London last week who are today to be charged under section 57 of the Terrorism Act.

"I don't think we have had a full and accurate statement from the government," he told the Today programme. "It has sort of come out in dribs and drabs, mainly through the newspapers."

The three men - Rabah Chekat-Bais, 21, Rabah Kadris, in his mid 30s, and Karim Kadouri, 33, all of no fixed address - were charged with the possession of articles for the preparation, instigation and commission of terrorism acts.

The charges relate to false passports and credit cards but not explosives or chemicals, a source said.

The deputy prime minister, John Prescott, yesterday dismissed claims that the men had been planning an attack on the underground. "There is no evidence whatsoever of bombs or gases in that circumstance. It has been elaborated on by the press," he said.